The yellow-eyed penguins generally lay two which are incubated by both parents – but, not at the same time! One penguin forages for food in the sea while the other penguin sits.
Females mate in the second or third year and males in their fifth or sixth year. The average age of breeding birds is seven or eight years but some breed successfully as old as 20 years.
It takes about 48 hours for each chick to peck its way out of the shell. It has an egg tooth at the end of its bill for the purpose.
Although about 1.54 eggs are actually hatched. Researchers have found they do not hatch because of a variety of problems including:
- The adults sitting on them and breaking them
- Eggs abandoned
- Embryonic death
- Eggs infertile
- Eggs missing from the nest
- Eggs found outside nest
It is thought that as the penguins get older they look after their eggs better!